Several reports have appeared concerning the accelerated lipolysis which occurs in adipose tissue of experimental animals and humans with cancer. The general mechanisms has been shown to be due to increased fatty acid mobilization rather than to decreased basal lipogenesis. The precise mechanism underlying increased lipolysis in tumor-bearing hosts remains to be determined. Lipolysis can be influenced, both positively and negatively, by endocrine factors. The goals of the proposed research are to determine if the presence of the Walker 256 carcinosarcoma, implanted intramuscularly, in rats results in altered secretion of various lipolytic hormones as well as the anti-lipolytic hormone insulin. The sensitivity of the adipose tissue from tumor-bearing and control rats to many of these hormones will also be studied. The production of a lipolytic factor by the tumor cells themselves will also be studied by culturing the Walker 256 cells and testing the culture medium for lipolytic activity.